I hope this refers to ring-0-like instructions such as x86 STI, and not some kind of OEM/manufacturer "you can only use this set of instructions if you pay us" type privilege?
https://github.com/riscv/riscv-isa-manual/blob/master/releas...
Alternatively in the PDF you would only need to look at the "Introduction" section for a minute.
https://github.com/riscv/riscv-isa-manual/blob/master/releas...